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Unable to retrieve pthread mutex symbols
- From: David Carter <dcarter at davidcarter dot ca>
- To: systemtap at sourceware dot org
- Date: Thu, 28 May 2009 12:43:27 -0230
- Subject: Unable to retrieve pthread mutex symbols
This is a continuation of the discussion that happened in response to
my blog posting. I'll summarize, but for the full discussion refer to http://davidcarterca.wordpress.com/2009/05/27/systemtap/#comments
Basically, I'm trying to debug mutex use in my program. I use the
pthreads version, which in turn uses futexes. Using the attached
systemtap script, I get the addresses of the futexes under contention,
but not the symbols associated with them. This makes debugging
difficult.
There are a few steps involved in setting up the test.
1. Using either FC10 or FC11, install the arm4 and arm4-devel
packages. These don't have SELinux support yet, so you'll either have
to disable it or make it permissive.
2. Add your user to the arm4 group
# usermod -a -G arm4 username
You'll have to log out and log in again for this to take effect.
3. Start the arm4 service
4. Compile the arm4 sample program
$ cc -o arm4test_hello_throughput arm4test_hello_throughput.c -larm4
5. Run the systemtap script while running the arm4 sample program. I
recommend starting the systemtap script before starting the sample.
The sample has an infinite loop so stop it after 30 seconds or so.Attachment:
arm4test_hello_throughput.c
Description: Binary data
Attachment:
futexes.stp
Description: Binary data
The output I get shows the hex addresses of the futexes rather than
the symbols. This makes it difficult to debug.
- Dave
----
Custom Software Solutions
http://www.davidcarter.ca
http://davidcarterca.wordpress.com